Figure 3.
Fig. 3. Comparison between the thermophile 8g8 (purple)
and WT (blue). (A) A superposition of the 315-324 and 265-275
loops. The His-322 Tyr
mutation introduces a direct interaction between the loops. The
315-324 loop is pulled closer to the active site to accommodate
the smaller substrate, allowing a 3.5-Å H bond between
Tyr-322 and the main-chain N of Ile-270. Additionally, the new
orientation of 315-324 allows an H bond between the side chains
of Ser-323 and Thr-326, stabilizing helix 12 and the 315-324
loop. (B) A superposition of WT and 8g8 shows the effect of the
Met-358 Val
mutation. In the absence of the His-322 Arg
mutation, the large reorganization of 265-275 is not seen.
Leu-362 and Ile-270 move to fill the cavity created by the
Met-358 Val
mutation.
Tyr
mutation introduces a direct interaction between the loops. The
315-324 loop is pulled closer to the active site to accommodate
the smaller substrate, allowing a 3.5-Å H bond between
Tyr-322 and the main-chain N of Ile-270. Additionally, the new
orientation of 315-324 allows an H bond between the side chains
of Ser-323 and Thr-326, stabilizing helix 12 and the 315-324
loop. (B) A superposition of WT and 8g8 shows the effect of the
Met-358